What Is a QR Code and How Does It Work?

A QR (Quick Response) code is a square grid of black and white modules that encodes data — a web address, Wi-Fi credentials, contact details, or plain text — in a form a camera can read in a fraction of a second. Unlike a traditional barcode, which only stores data along one line, a QR code stores data across two dimensions, which is why it can hold far more information in the same amount of space.

How a QR code stores information

Every QR code is built from a fixed set of parts: three large squares in three corners (the 'finder patterns') that let a scanner detect the code's position and orientation at any angle, a smaller alignment square that corrects for distortion, and a grid of data modules that encode the actual content as binary — each square is either 'on' (black) or 'off' (white). A built-in error-correction layer means the code stays scannable even if up to 30% of it is damaged, dirty, or covered by a logo.

What can be inside a QR code

• A website URL — the most common use, for menus, product pages, or landing pages.
• Wi-Fi network credentials, so a phone joins the network the instant it scans the code.
• A contact card (vCard) that saves a name, phone, and email straight to the address book.
• Plain text, a phone number, an SMS or WhatsApp message, a calendar event, a map location, or — in Brazil — a Pix payment key.

Static vs dynamic QR codes

A static QR code encodes its final content directly — what you generate is what will always be scanned, forever, for free, with no expiration. A dynamic QR code instead points to a short redirect URL controlled by a service, which lets you change the destination later and track scan counts, usually for a recurring fee. For most personal and small-business use — a menu, a business card, a flyer — a static QR code is simpler, free, and never depends on a third-party service staying online.